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Earth and Space 6-8 / Week 09 / Wednesday
3/6
Week 09 · Rocks Change

Wednesday

Sky Deck Lab: Sort and model
// Energy flows, matter cycles, rocks turn into other rocks
⏱ about 20 min

Wednesday: Sky Deck Lab: Sort and Model

The crew walks the path along the yard with a paper bag. "Only loose ones," Raven reminds Rocket, who is already crouching.

He holds up a flat gray rock that splits into thin sheets. "Layers! Sedimentary!"

"What do you notice when you tilt it?" Raven asks. "The sheets shine. And the lines do not match the flat side."

Nova hovers over the rock. "Shale can be squeezed into slate," she says. "Slate splits into flat sheets too. Look for both clues."

Rocket frowns, then grins. "So I need a table, not a guess."

Back at the Sky Deck, Raven rules three columns: grains, layers, crystals. Nova hums. "Observe first. Decide last."

Your mission

Today you sort a few loose rocks by what you can see, then build a rock cycle model from cards.

You are looking, not testing. No hammering, no scratching, nothing in your mouth.

The survey tells collectors to label specimens as they are collected and record the place at once. You will do the same in your table.

  • Four to six loose rocks from a path, a beach or your own yard
  • A paper bag or small box, and a sheet of newspaper to work on
  • Six index cards or squares of paper, a pencil and a marker
  • A ruler, a magnifier if your family has one, and your Sky Log
  • Soap and water for your hands afterward
Safety first
Pick up only loose rocks from a path, a beach or your own yard. Never take rocks from a park, a garden bed or someone else's property.
No hammering, breaking or scratching rocks. Looking is the test.
Nothing is tasted or licked. Keep rocks away from younger children.
Wash your hands after handling rocks, sand or soil.
  1. Spread the newspaper on the Sky Deck and set out your rocks in a row. Number them with the marker on a paper tag.
  2. Hold each rock in good light. Look for grains you can see, layers or bands, and sparkling crystals.
  3. Measure the longest side of each rock in centimeters and write it in your table.
  4. Fill the table: grains, layers, crystals, and your best group with a reason.
  5. Write one card for each rock group: igneous, sedimentary, metamorphic. Write three more cards: magma, sediment, melting.
  6. Arrange the cards in a loop on the table. Draw arrows between them on scraps of paper and label each arrow with a process.
  7. Place each rock beside the card for the group you chose. Check that every arrow out of a card makes sense.
  8. Copy your finished loop into your Sky Log before you put the cards away.
PREDICT BEFORE YOU SORT
  • Read the question.
  • Tap your answer.
A rock with sand-sized grains in flat layers most likely belongs to which group?
A rock with large interlocking crystals and no layers most likely formed how?
Rock numberLongest side (cm)Grains you can see?Layers or bands?Crystals?Best group and reason
1
2
3
4

Reading your clues

The survey says slowly cooled magma grows crystals and makes a coarse-grained rock. Rapidly cooled magma makes a fine-grained rock with extremely small crystals.

Sedimentary layers are normally parallel or nearly parallel to Earth's surface. Sand and gravel on beaches look like the sandstone and conglomerate they will become.

Some metamorphic rocks are strongly banded or foliated. Foliated means certain mineral grains line up in parallel, giving a striped appearance.

A rock walk gives you a guess, not a certainty. Geologists check with maps, museums and tests you are not doing today.

What the lab showsTrue or false?
Looking at grains, layers and crystals can suggest a rock's group.?
A striped, banded rock is a clue for metamorphic rock.?
You can be certain of a rock's group just by looking.?
The six cards in a loop are a model of the rock cycle.?
WHY THIS EXERCISEThe standard asks you to develop a model of cycling materials. Your card loop is that model, and your rocks are the evidence.
How many rock groups did you write cards for? Type a number.
WHY THIS EXERCISEEvery rock cycle model has these three stations, however many arrows you draw.
Sketch your card loop with its arrows. Then draw your most interesting rock beside the card where you placed it.

A model built from your own evidence. Tomorrow you read the survey's own descriptions as a data table.

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